ICT2 - Information: Management and Manipulation
Processing Different Types of Data
Interactive Processing
The processing system responds immediately whenever a change is made.
Example 1: When booking a seat on an airline, the seat is booked immediately. This is to avoid problems of double-booking.
Example 2: When you phone up to renew your car insurance, you are insured straight-away. Otherwise, people would be driving around uninsured.
Interactive processing may also called ONLINE PROCESSING or PSEUDO REAL-TIME PROCESSING.
Transaction Processing
Transaction Processing is similar to interactive processing. Data for each transaction is processed very shortly after the transaction occurs. A transaction is completely processed before the next transaction. This may result in a particular transaction having to wait while an earlier one is processed. The delay will usually be short. An example might be holiday bookings where a second transaction will not be initiated until the first is completed to avoid the possibility of double booking. Transactions are processed in the order they occur. This type of processing may be (and often is) interactive.
Real-Time and Pseudo Real-Time Processing
Real-time processing is when a computer responds immediately to an event, e.g. a computer that controls a plane has to respond immediately to changes in air-pressure, wind, speed and so on, an airline booking system makes the booking immediately so that nobody else can book the same seat.
A computer in a library or a supermarket performs transactions more or less immediately. A delay of a few seconds is acceptable. This is called pseudo real-time processing.
Case Study: Example of BA Booking System
Batch Processing
BATCH PROCESSING - the balance is not updated until late at night when the day's transactions are processed in a batch.
Some transactions need to be processed straight away but others can wait to be processed in a batch e.g. payment of gas bills. It is a good idea to processes these transactions in batch mode because it is more economical and because you can check for errors.
When faced with a question about batch processing in an exam, be sure to make the following points:
The documents are collected over a period of time
The batch processing is scheduled for a certain time
Batch processing can take place when computers would otherwise be idle
Batch processing is suitable for a large number of documents of the same type
Stages in Batch Processing
Batch processing is where a group of similar transactions are collected over a period of time and processed in a batch.
1. Paper documents are collected into batched (e.g. of 50), they are checked, control totals/hash totals are calculated and written into a batch header document.
2. The data is keyed offline from the main computer and it is validated by a computer program. It is stored on a transaction file.
3. Data is verified by being entered a second time by a different keyboard operator.
4. The transaction file is transferred to the main computer.
5. Processing begins at a scheduled time.
6. The transaction file may be sorted into the same sequence as the master file to speed up the processing of data.
7. The master file is updated.
8. Any required reports are produced.
Criteria for Choice of Processing Mode
The following should be considered:
Whether the information obtained needs to be completely up-to-date at all times
The scale of the operation - batch processing is well-suited to large volumes of data.
Cost - real-time systems are generally more expensive.
Computer Usage - batch systems make use of spare computer capacity because they process at times when the computers would otherwise not be used.
Advantages and Disadvantages
With an online/interactive system, the data is always up-to-date and there is less need for paperwork.
However, the lack of paperwork causes a problem for auditors. Checking for accuracy can be difficult.
Processing Different Types of Data
Representing Numbers
Each character on the keyboard has a corresponding ASCII code, which is sufficient for input and output but no use for arithmetic. Therefore, numbers, which are to be used in a calculation, are held in a different format, in binary numbers. For example, telephone numbers in a database are usually held in a text field because there is no need to calculate them.
Digitised Sound
Sound (music or speech) can be inputted via microphone, CD, electric keyboard and it can then be processed by the computer.
An A to D converter is required (this job is done by the soundcard). An A to D converter converts analogue to digital. Sound waves, which are continually variable are analogue but they have to be converted into 1s and 0s (digital format) for the benefit of the computer.
The quality of the soundcard determines the quality and accuracy of the sound produced. The higher the sampling rate, the greater the quality. The resolution of the sound card (8 bit, 16 bit, 32 bit, 64 bit etc.) determines how accurately the amplitude of the sound can be measured. The sound card also has a built in synthesiser for producing music and sound effects.
MIDI (Musical Instrument Digital Interface)
MIDI is an industry standard applied to musical instruments. Adding a MIDI interface to a computer allows it to communicate with instruments like MIDI keyboards, drum pads etc. MIDI synthesised music is very compact and, therefore, small files are produced. This is because the data is stored as instructions (about pitch, length of sound etc) rather than recorded sound. The file is loaded on a computer and it can be edited e.g. pitch or speed can be altered, a keyboard solo can be converted into a guitar solo, balance between instruments can be altered etc.
Bitmapped and Vector Graphics
The screen is divided into a grid of tiny squares. Each square is called a pixel (picture element). High resolution screens have more pixels than low resolution screens. The pixels have to be held in memory and this is stored initially on the graphics card. Windows Paint produces bitmapped graphics files (.BMP format). Scanners produce bitmapped graphics.
Vector graphics are also called object orientated graphics. These consist of real geometric data rather than graphic data. A line is defined by endpoints, length, width and colour rather than by pixels. Vector graphics are produced by applications like Corel Draw.
Bitmapped Graphics v Vector Graphics
Bitmapped graphics become jagged when stretched and resized.
Bitmapped graphics don't transfer well between computers because of different screen resolutions.
Bitmapped graphics suffer degradation when they are zoomed in on.